 # Increase and Decrease Numbers by the Given Percentages

In this worksheet, students practise decreasing numbers by the given percentages. They can use a calculator to help. Key stage:  KS 3

Curriculum topic:   Number

Curriculum subtopic:   Define, Interpret and Compare Percentages

Difficulty level:   ### QUESTION 1 of 10

In this worksheet, we will learn how to increase and decrease numbers by a given percentage using a calculator.

Methods and Examples

A whole number or quantity is 100%.

Increasing a number by 10% gives 100% + 10% = 110% of the number or 1.1 × the number. So 25cm increased by 10% is 1.1 × 25 = 27.5 cm.

Decreasing a number by 15% gives 100% - 15% = 85% of the number or 0.85 × the number. So 25cm decreased by 15% is 0.85 × 25 = 21.25 cm.

Increase 55 by 13%.

Decrease 57 by 11%.

Increase 35 by 7%.

Decrease 95 by 13%.

Increase 68 by 42%.

Increase 89 by 38%.

Decrease 19 by 35%.

Decrease 66 by 34%.

Increase 85 by 19%.

Decrease 51 by 41%.

• Question 1

Increase 55 by 13%.

62.15
EDDIE SAYS
13% increase gives 113% of the original. This is a multiplier of 1.13 1.13 x 55 = 62.15
• Question 2

Decrease 57 by 11%.

50.73
EDDIE SAYS
11% decrease gives 89% of the original. This is a multiplier of 0.89 0.89 x 57 = 50.73
• Question 3

Increase 35 by 7%.

37.45
EDDIE SAYS
7% increase gives 107% of the original. This is a multiplier of 1.07 1.07 x 35 = 37.45
• Question 4

Decrease 95 by 13%.

82.65
EDDIE SAYS
5% increasedecrease gives 95% of the original. This is a multiplier of 0.95 0.87 x 95 = 82.65
• Question 5

Increase 68 by 42%.

96.56
EDDIE SAYS
42% increase gives 142% of the original. This is a multiplier of 1.42 1.42 x 68 = 96.56
• Question 6

Increase 89 by 38%.

122.82
EDDIE SAYS
38% increase gives 138% of the original. This is a multiplier of 1.38 1.38 x 89 = 122.82
• Question 7

Decrease 19 by 35%.

12.35
EDDIE SAYS
35% decrease gives 65% of the original. This is a multiplier of 0.65 0.65 x 19 = 12.35
• Question 8

Decrease 66 by 34%.

43.56
EDDIE SAYS
34% decrease gives 66% of the original. This is a multiplier of 0.66 0.66 x 66 = 43.56
• Question 9

Increase 85 by 19%.

101.15
EDDIE SAYS
19% increasedecrease gives 119% of the original. This is a multiplier of 1.19 1.19 x 85 = 101.15
• Question 10

Decrease 51 by 41%.

30.09
EDDIE SAYS
41% increasedecrease gives 59% of the original. This is a multiplier of 0.59 0.59 x 51 = 30.09
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